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Enzyme activity and dynamics in near-anhydrous conditions

Murielle Lopez¹, Vandana Kurkal-Siebert², Rachel Dunn³, Moeava Tehei⁴, John Finney⁵, Jeremy Smith⁶ & Roy Daniel⁷

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1. University of Waikato
2. BASF
3. Manchester Interdisciplinary Biocentre, Faculty of life science
4. Australian Institute of Nuclear Science and Engineering and University of Wollongong, School of Chemistry and Centre for Medical Bioscience,
5. University College London, Physics and astronomy
6. UT/ORNL, Center for Molecular Biophysics
7. University of Waikato, Biological Sciences

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Date:

Received 21 October 2009 14:13 UTC; Posted 28 October 2009

Subjects:

Biotechnology, Chemistry

Tags:

• Protein hydration
• Protein function
• protein dynamics

Abstract:

Water is widely assumed to be essential for life 1, although the exact molecular basis of this requirement is unclear 2-4. Water facilitates protein motions 5-9 and although enzyme activity has been demonstrated at low hydrations in organic solvents 10-13, such non-aqueous solvents may allow the necessary motions for catalysis. To examine enzyme function in the absence of solvation and bypass diffusional constraints we have tested the ability of an esterase to catalyse alcoholysis as an anhydrous powder, using a closed reaction system in which the substrates and products of the enzyme reaction are gaseous 14-15, and where the water content can be well defined 16. At hydrations equivalent to 3 (±2) molecules of water per molecule of enzyme, activity is observed that is several orders of magnitude greater than non-enzymatic catalysis. Neutron spectroscopy indicates that the fast (≤nanosecond) global anharmonic dynamics of the anhydrous functional enzyme are heavily suppressed. The results indicate that neither hydration water nor the solvent-activated fast anharmonic dynamics are required for enzyme function. An implication of these results is that one of the essential requirements of water for life may lie with its role as a diffusion medium rather than any of its more specific properties.

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This document is licensed to the public under the Creative Commons Attribution 3.0 License

How to cite this document:

Lopez, Murielle, Kurkal-Siebert, Vandana, Dunn, Rachel, Tehei, Moeava, Finney, John, Smith, Jeremy, and Daniel, Roy. Enzyme activity and dynamics in near-anhydrous conditions. Available from Nature Precedings <http://hdl.handle.net/10101/npre.2009.3884.1> (2009)

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